1. Field of the Invention
The invention relates to an electric driving tool.
2. Related Art
There is known an electric driving tool which includes a plunger normally energized downwardly by a spring and a driver fixed to this plunger, and in which the plunger is released after it is pushed up and the driver is driven by an energizing force of the spring to drive a fastener.
In this electric driving tool, the driver waits at a given wait position when not driven.
Patent Reference 1: JP-B-02-044675
Patent Reference 2: U.S. Pat. No. 4,807,793
Patent Reference 3: JP-U-62-081581
Patent Reference 4: JP-B2-3344454
For example, in tools disclosed in Patent Reference 1 and Patent Reference 2, a driver waits at a bottom dead center position.
In a tool disclosed in Patent Reference 3, a driver waits at a top dead center position.
In a tool disclosed in Patent Reference 4, a driver waits near a top dead center position.
According to the tools of Patent Reference 1 and 2, since the driver is structured to wait at the bottom dead center position, there is found a problem that, in a driving time, the driver must be moved to the top dead center, which worsens the tool's response from a trigger operation to a driving operation.
According to the tools of Patent Reference 3, since a plunger and the driver are structured to wait at the top dead center position, when a motor rotates with poor precision, there is a possibility that, although the motor must be so rotated as to stop the driver at the top dead center position, it can be rotated in error to move the driver to its driving position. This raises a danger that the driver can drive the fastener in error. When the driver's waiting state is removed due to such unexpected malfunction, the driving operation is carried out instantaneously. Therefore, a mechanical preventive mechanism or the like is necessary.
According to the tool of Patent Reference 4, since the driver is structured to wait near the top dead center, the response time problem does not arise and, and since the driver stays downward of its driving portion, there is not a danger that the driver may drive a fastener in error.
However, according to the tool in which the driver is structured to wait near the top dead center position such as the tool of Patent Reference 4, the driver only contacts with a portion of the connected fasters near heads thereof. Therefore, when the residual quantity of the connected fasteners becomes small, there is a possibility that only leading end portions of the connected fasters not in contact with the driver may be pushed forward and thus these connected fasteners may be inclined obliquely within a magazine (see FIG. 11). If new connected fasteners are additionally loaded into the magazine while the connected fasteners are still inclined obliquely within the magazine, there is a possibility that the head of the last one of the obliquely inclined connected fasteners can be superimposed on the head of a leading one of the added connected fasteners, whereby a fastener storing portion cannot be closed.
This problem can be solved by increasing a guide margin of a guide member for holding the leading end portions of the fasteners within the magazine. That is, if the guide margin of the guide member is increased, although there is a possibility that the connected fasteners, the residual quantity of which has decreased, is inclined obliquely within the magazine; even in this case, the obliquely inclined connected fasteners and the added connected fasteners can be prevented from being superimposed on each other.
However, with such increased guide margin, a space necessary for loading the connected fasteners into the guide member or taking out them therefrom is increased. That is, when the connected fasteners are loaded into or removed from the guide member, the connected fasteners must be moved in an axial direction more greatly than the guide margin, which makes it necessary to increase a clearance for moving the fasteners in such axial direction.
Thus, when the response performance and safety are taken into account, the driver may preferably be made to wait at an intermediate position between the top and bottom dead centers. However, when the driver is made to wait at the intermediate position between the top and bottom dead centers, there is a problem that the connected fasteners, the quantity of which is decreased, may be inclined obliquely within the magazine. To solve this problem, the guide margin of the guide member may be increased. But, this raises a problem that the size and weight of the whole driving tool are increased.